The present invention relates to an inlay sole comprising a soft-elastic lower layer, a flexible cover layer, and separable knobs. Of U.S. Pat. No. 4,047,310 a sandal with an orthopaedically formed bending-resistant sole is known, a relatively thick soft-elastic layer of rubber or plastic being glued to its upper side. In this upper layer a large number of pegs, arranged uniformly in rows over the entire sole surface, is permanently embedded, its upper rounded ends protruding from this layer and exerting a massaging effect on the foot sole and/or on certain sole areas. The pegs consist of a hard plastic material and support themselves by a conically enlarged foot on the bending-resistance running sole.
In another sandal known a great number of pressure elements are pressed from above into the recesses, formed in a pregiven pattern on the entire surface of the insole or footbed sole, in order to reach acupressure effects. The knob-like pressure elements have a cylindrical or locally thickened shaft and an enlarged flat head with rounded surface. The pressure elements having a punctual acupressure effect may result in an individual influence on the nerves ending in the foot sole and/or they may be arranged in reflex zones corresponding to the foot sole's division. A basic disadvantage of these known shoe embodiments consists in that the acupressure effect is restricted to a certain shoe and the desired stimulation effect reduces after about two hours of wearing, thus requiring the shoes to be changed several times a day. Due to the insufficient anchoring possibility of its shafts, the exchangeable pressure elements cannot be used for stylish shoes, in particular ladies' shoes, having thin running soles. DE-OS 35 20 956 describes a reflex inlay sole in which a great number of pins is arranged uniformly and at larger distances in the sole, protruding over the sole's upper side for stimulation of certain reflex points on the foot sole of the wearer. The inlay sole consists of a lower layer of a pressure-elastic deformable material and of an upper tissue layer, having a large number of penetration openings for, the rigid pins made e.g. of wood. The wooden pins have a disk-like enlarged foot, which serves as a support on the elastic layer and sinks into this layer when pressure is applied. The two flexible layers are only interconnected at their outer edge by a seam, such that relative displacements of the two layers resulting from rolling on the foot during walking may lead to a tilting of the rigid wooden pins, resulting in painful pressure points.
The present invention is therefore based upon the task to improve an inlay sole of the known kind in such a way that an easy fixing and/or changing of the knobs in the desired zones is guaranteed over a long period of time and that the perfect function of the inlay sole with knobs is also guaranteed over a long period of time.
This object is solved by the features of the present invention.
Due to the fact that the enlarged foot of the knobs is fit into a corresponding recess in the lower layer and that the knobs have an enlarged head with rounded upper side, its diameter being slightly larger than the hole diameter, supporting itself with its edge on the flexible cover layer, it is possible to perform the insertion and/or removal of the knobs easily and quickly and a secure fixation of the knobs over a very long period of time is guaranteed.